Improvement in steam vacuum-pumps



W. E. PRALL- & D. A. BURR.

STEAM VACUUM PUMP.

No.172,654. Patented J-an. 25*1876,

iz' zz AQUOMETER m'ffiesses 4 UNITED STATES PATENT Orrrorec WILLIAM E.PRALL AND DAVID A. BURR, OF WASHINGTON, D. G.

IMPROVEMENT IN' STEAM VA'CUU M-PU MP8.

Specification forming part of LettersPatent No. 172,654, dated January25, 1876 application filed November 21, 1873.

CASE B.

To all whom it may concern Be it known that we, WILLIAM E. PRALL tainImprovements'in Steam Vacuum-Pumps,

of which the following is a specification:

Our invention involves an improvement upon the original invention ofWilliam E. Prall, described in his Letters Patent dated December 19,1871, andreissued November 5, 1872, No. 5,138,,in which the admission ofsteam to a double-acting steam vacuum-pump is automatically controlledby means of a diaphragm, movable piece, or piston, so placed in achannel of communication between the working chambers or cylinders ofthe pump as to be moved by the reduction of pressure produced withineither of them by reason of the sudden vent of the steam through, andits partial condensation within, the discharge-port of the cylinders;and it consists in so constructing the said piston or movable piececontrolling the admission of steam to the pump as that a portion of itssurface exposed to the pressure of the steam passing through it shall beopposed to a corresponding fixed surface exterior thereto, in suchmanner as that the reaction or recoil of the steam against such fixedexterior surface shall tend to move the piston or movable piece awaytherefrom toward the open port to close the'same, and shall operate toproduce such a movement so soon as a reduction of pressure takes place,as aforesaid, in that chamber of the pump with which said portcommunicates.

In the accompanying drawings, Figure lis an end view, and Fig. 2 avertical central longitudinal section, of our improved pistonvalve; Fig.3, a front elevation, and Fig. 4 a side view, of our improved aquameter,or steam-pump, operated by said valve. Fig. 5 illustrates a modificationof the valve.

B is a metallic shell or casing, through which communication isestablished between the Working chambers A A, Fig. 3, of our improvedsteam-pump when properly attached or connected thereto. (See Fig. 4.) (Jis a cylindrical chamber, formed longitudinally within the casing B, andwhich is closed at either end by plugs D D, screwing therein.

(See Fig. 2.) 'ciently within the casing to admit of the form ation ofan annular groove or channel, 0 0, about the same, free communicationbeing established between said channel in each plug and the chamber 0 bymeans of perforations ff through the. inner face of the plug, andoutwardly through thecasing bymeans of apertures'or' eduction-ports g g,arranged to be in registerwith said annulargroovesec when the plugs arescrewed into place, as shown in Fig. 2.

By securing the casing B upon the steampump A A, Figs. 3 and'et, sothat'the apertures g g shall communicate, respectively, with the twochambers thereof, a channel of communication is thereby establishedbetween said chambers through the apertures g g, grooves e c, andcylindrical chamber 0.

An aperture or steam-induction port, h, is also formed centrally in theperimeter of the chamber G, and suitably re-enforced to receive a pipeconnecting from the boiler or steamgenerator.

K is a piston or movable piece, fitted toplay freely Within thecylindricalchalnber G, and which operates to close the channel ofcommunication established, as aforesaid, between the chambers of thepump through the chamber 0. This piston is so proportioned in length asthat, when either end thereof is against the correspondingend of thechamber 0, its opposite end shall project beyond the steam-inductionport It, so that said port is at all times covered by the perimeter ofthe piston, and yet leave an open space, w, beyond and between it andthe end of the chamber, as shown in Fig. 2. m is an annular groove cutcircumferentially about the piston, of such width as that it shallcommunicate freely with the steam-port h when the movement of the pistonK is completed in either direction, and of such depth as that, itstransverse area shall at least equal that of said steam-port. n, Fig.2,'is an aperture pierced longitudil'lally centrally through the axis ofthepiston, of a diameter somewhat less than that of the steam-port h,and which communicates with the annular groove m by means of radialholes 1'.

These plugs are extended suffiner end of the chamber 0, allcommunication is thereby closed between the steam-port it (through thepiston and the interior of the chamber C) and the eduction-port g atthat end of the casing, free communication being in' tIi -ineantimeestablished from said steampor 'h withthe op'posi'teeductioh-port gthrough the apertureih the piston, the'space fW, in the end of thechamber [0, and the-open,

ingsin the plug-Due illustratedby t-h et jar- 'rows in Fig. 2,.u." v I 43 SS are recesses so formed in each end of the piston K,'.ahout thecentral aperture there- I in; asthat when either end of/the piston isvclosed by contact with the inner face of the GOI'I'6SpOl'l(llilg plug D,thest'ea'm may pass 'into said recess between the face of the pis ton and'the face of the 'plug as shown in Fig.2. That portion of the surfaceof the piston included. in said recess S is thus opposed toacorresponding surface of the plug exterior thereto,- when the end of thepiston is in contact with said plug, and the steam passing through thepiston passes readily into'said recess to react or recoil between saidsurfaces; This tendency ofthe steam reacting against the fixed surfaceof the plug upon the surface of the piston opposed thereto in the recessS, and operating to force the piston away from its seat against'saidplug, exerts a constant force in that direction proportioned to thepressure of the steam within the piston, so long as the steam findsve'nt through it. I f X X are springs, which may be employed either asan auxiliary to the reactive steampressure developed in the recesses SS, as described, or in the stead of, and as a substitute for, the same.'These springs, when used, may be placed and secured in recesses formedin the facesflof the piston K, as shown in Fig. 2, or in the counterpartfaces of the plugs D D, forming the ends of the chamber (3, so as to becompressed when the face of the piston comes into contact with the faceof the plug or end of the chamber.

It is evident that, instead of carrying the 'steamway from the annularrecess m to a central passage, 01, in the piston, to communicate withsteamways formed near the outer edge or circumference of the plugsforming the ends of the chamber 0, as illustrated in Fig. 2,perforations may be made through the rim of the said annular recess m,to communicate with steamway's formed in the center of the plugs, asshown in Fig. 5, the recess S in this last case beingmade of an annularform on each face of the piston K, instead of centrally thereon.

In the Working of our pump and the operation of our sai'd piston-valveK, the reactive "force of the steam within the recess S, (or theresilient power of the spring X in the stead thereof,) tending to forcethe piston from its seat, and to open consequently the steamway closedthereby, is counterbalancedwhile the steam. is operating to dischargethe water from the opposite, cylinder A-hot only by the superiorpressure within 'said cylinder,

(and consequently within the space W in the chamber 0, acting againstthe entire face of the piston at that end to force it toward thepassagesat the opposite end, communicating with the cylinder A of lesserpressure, so that it shall close them,) but also to a greater or lessextent by the recoil of the steam issuing in-a jet from the open end ofthe piston. So soon, however, as the pressure in the dischargingcylinderA is reduced by the sudden vent of. steam therefrom, as hereinhefore setforth, to a degree less than that in the opposite closed cylinder A",the constant reactive or resilient power of the steam, or of theconfined spring X, or of the two combined, as the case maybe, uniteswith the superior pressure upon the same side of the pistonthrough thechannels 9, e, and f, to

throw the pistonagainst the opposite end of the chamber, and therebyclose the ports into the exhausted cylinder A and open thosecommunicating with the cylinder A, Whereupon the same condition is at'once established upon that side as previously existed on the other.

We claim as our invention- 7 In combination with a grooved and per-'forated piston or valve, K, controlling the admission of steam to asteam andvacuum pump, a recess or steam-space, S, formed within oropposite to the outer face of each end 'of said valve, to communicatethrough said valve with the steam-supply pipe of the pump,substantiallyas' and. for the purpose herein set forth.

W. E, PBALL. Witnesses: DAVID A. BURR.

ROBT. G. LOUGHERY, S. M. PooL.

